Treatment of copper liquors.



UNTT 1 riars arias? a ibi TREATMENT 0F COPPER LIQUOBS.

No Drawing.

To all whom it may concern:

Be it known that 1, JOHN HERBERT TI-IWAITES, M. Se a subject of the King of Great Britain, residing in Peterborough, and whose post-office address is Market Chambers, Peter-borough, in the county of Yorthampt-on, England, chemical engineer, hare invented certain new and useful Improvements in the Treatment of Copper Liquors, of which the following is a specification.

The known application of Zinc sulfid as a precipitant for copper in copper liquors pre sents certain advantages. among which is the fact that little or no iron accompanies the precipitated copper suliid.

According to the present invention the zinc sulfid is used in the form of a mixture at barium sulfate and zinc sulfid. such as is obtained by precipitating a solution of zinc sulfate with barium sulfid. This product, which must not have been dried or calcined, is used in manner substan ially similar to that in which zinc sulfid has been used, to preci itate the copper as sulfid from liquors containing copper. whereby Zinc passes into solution and barium sulfate remains mixed with the precipitated copper sulfidr This mixture is oxidized as far as possible, in known manner, such as by drying and heating the air. A large proportion of the C113 is oxidized to (71130 during drying, the oxidation of the remainder being completed in a few hours at 210 to 250 C. The mixture containing the copper sulfate is then leached with Water to extract the latter, such quantity of sulfuric acid as may be necessary to convert any copper oxid that may be present into sulfate. being added. preferably to a portion only of the water used for leaching. The residue of barium sulfate is new converted into suhid by thorougl mixing the sulfate with powdered coal and. heating the mixture in a suitable furnace' The material :1 tier it has cooled is leached with Water and filtered the filtrate being used to precipitate the zine from the liquor from which the copper has been removed. This liquor must contain a dissolved sulfate. which may be present as an original constituent of the liquor or may be added at this stage or pre viously, otherwise barium sulfate would not be precipitated together with the Zinc sulfid,

as snecessary :lor the process. The mixture ot zinc sultio and barium sulfate thus pro- Specification of Letters Itatent.

Application filed December 27, 1911.

Patented Aug. 5,1Q1l3.

Serial No. 668,136.

duced is then used to precipitate copper from another batch of copper liquor. This precipitation may be represented by the chemical equation (infil -H5113, B2180 CuS, BaSOfl-ZnSO The oxidation of copper sulfid to copper sulfate may be represented by the chemical equation CuS+2O :CuSO

The reduction of barium sulfate to barium suliid by carbon may be represented by the chemical equation Copper liquors of the kind in question generally contain sufficient zinc to make up for losses in the process, so that it is then only necessary to introduce a little fresh bariumsulfate periodically to make up for loss of this material.

I wish it to be understood that. by barium sulfate in this specification and in the claims thereto I mean not only the substantially pure compound but any commercial mixture thereof with strontium sulfate and indeed substantially pure strontium sulfate itself.

The main object of the process is the production of copper sulfate substantially free from iron. In this connection the use of the mixture of barium sulfate and zinc sultid presents the advantage that the precipitant can be used repeatedly Without import of fresh material other than the fuel used to reduce the barium sulfate to sulfid. More over, the copper snlficl being spread over a basis of barium sulfate is more rapidly and completely oxidized than is the case with the dense copper sultid precipitated by zinc sulfid alone. The presence of the "BaSO, causes the (la and the ZnS respectively to settle rapidly. Whereas in the absence of B5130. each forms a bulky precipitate very difficult to treat. Hence the process as a whole is more rapid than any hitherto devised and the capital locked up in plant, and floating stock of copper is comparatively small.

The copper liquors of the ordinary wet copper process practically always contain some zinc but not much iron. After copper has been precipitated from them by scrap iron in the usual manner the large amount aim oi iron thus dissolved prevents economical iron originally present in the copper liquor sultid unchanged.

its

is generally insuftlcicnt to interfere With the recovery of the zinc. Now it will be seen that in the process according to this invention, the zinc in the copper liquor-serves to make up any loss of the zinc which is used in the form of sulfid tor precipitating the copper, but there is generally more'zinc then is sufficient for this purpose and this excess may be Worked up in one of several Ways. For example, it may he precipitated: With soda ash to produce crude zinc, oxid for si'nelting, or it may be treated with bleaching powder to precipitate any iron that may be present, and the letter having been filtered oil, the filtrate may bc'precipitsted in the known manner for producing lit-hopone.

A further advantage of the process is thatvit renders very easy the recovery of any silver which the liquor may contain.

1 have found that the silver contained in the copper liquor is precipitated as sulfid tog-ether with the copper sullid when the mixture of barium sulfate and Zinc sulfid is added: indeed, generally, the Whole of the I silver is precipitated with the first partot' the copper. r iccording to the invention this mixture of sulfidsand baruuu sulfate is treated so as to oxidize the copper suliid While leaving the, silver in a term insoluble in Water or dilute acid, still mixed with the barium sulfate; the oxidizedv copper sultid is then removed "from the barium sull ute, and the latter is treated by a suitable method for extracting the silver Without destroying the barium sulfate which is afterward reduced to barium sulfid for further use as herciubefore described. Preferably the mixture of barium sulfate. copper sullid and silver sulfid is heated sufficiently in air, in ltnou'n manner, to convert the copper sulfid into sulfate leaving the silver TllfillllSS is. then first leached with Water to dissolve copper sulfate and finally with dilute sulluric acid to dissolve copper oxid, if any of this has been formed.

The best method at present known of treating the barium sulfute containing the silver sulfid is to subject it to the action of e chlorid or mixture adapted to convert the silver sulfid into chlorid and then to leech it With u solvent for silver ehlorid; or the converting agent end the solvent mey be used together. i A suitable converting agent is one. of the chloride oft w ite or u ramture of them, 'cuprous chimed rather better thencuprio chlorid; brine or c soluble thioeultete is the best solvent conversion ct silver uuhhd into noeenou chlorid by uctionot cup'rous chlorid inuy represented by the chemical equation I The best procedure is to treat the barium sulfate containing the silver sulfid with a solution of a chlorid of copper and common ver from the solution of silver chlorid may be used, such as precipitation by zinc. The preferred procedure is to allow the barium sulfate from which the copper sulfate has been leached to remain in the filter press and to run into the press brine containing cuprous chlorid, sufficient to convert into chlorid the silver sulfid in the barium sulfate. -After the press has been at rest for, say, an hour, brine or a strong solution of sodium thiosulfate is pumped through it to obtain at solution containing silver chlorid. The buriuni sulfate is then reduced to sulfid' and returned to the process as hereinbefore described.

l lsving thus described the nature of my said invention and the best means I know of carrying the same into practical efi'ect, I ,(l2tllflI 1. A process tor treating copper liquors, which process consists in first adding to the copper liquor a mixture of barium sulfate and zinc sulfid which has not been dried,

then removing the copper sulfid from the mixture of barium sulfate and copper sulfid' thus produced, then reducing the barium sulfate to barium sulfid, and then adding the barium sulfid to the liquor Wheretrom the copper sulfid has been precipitated so as to obtain a mixture of barium sulfate and zinc sulfid for re-use.

2. A process for treating copper liquors, which process consists in first adding to the liquor a mixture of barium sulfate and zinc sulfid which has not been dried, then heating in air the mixture of barium sulfate and copper sulfid thus produced, then leaching the oxidized mixture so as to remove from it the copper compounds, then reducing the barium sulfate to barium sulfid, and then adding the barium 'sulfid to the liquor from which-the copper sulfid has been precipitated spas-to obtain a. mixture of barium sulfate and zinc sulfid for re-use.

3. A process for treating copper liquors, which process consists in first adding to the liquor a mixture of barium sulfate and zinc sulfid, which has not been dried, then removing the copper sulfid from the mixture ct hsriuuuv sulfate and copper sulfiol thus produced, then reducing the barium sulfate then adding the barium uuhtcl to the liquor which the cop r he precipitated, then remg the honor the mature ell" heriu'rn cut finallv Working up. the liquor to obtain Zinc:

fate and zinc sulfid thus produced and compounds therefrom.

LA process for treating copper liquors, which process consifts in first adding tothe liquor a mixture of-barium sulfate and zinc sulfid which has not beendried, then removing the copper sulfid from the mixture-of barium sulfate co per sulfid and 1 silver sulfid, thus pro need then treating the mixture of barium sulfate and silver sulfid with an agent adapted to convert the silver sulfid into a compound solublein asuitable solvent, then leaching the mixture of barium sulfate-and. soluble silver compound with v such solvent, :then' reducing the barium-sulfate. to barium sulfid, and then adding the barium, sulfid to the liquor from which the copper sulfid has been precipitated so. as to obtain a mixture of barium sulfateand zinc sulfid forre-use.

- 5; A process fort'rea-ting copper liquors, which process consists in'first: adding tothe liquora mixture of barium sulfate and zinc sulfid which has not been dried, then heatingin air the mixture of barium sulfate, copper which process consists in firstadding tothe liquor a mixture of barium sulfate and zinc.

sulfid which has not-been dried, then removing the copper sulfid'from the 5 mixture ofbarium sulfate, copper sulfid and 5 silver sulfid thus produced,-then'treating the mix ture of barium sulfate and silver sulfid with an agent adapted to convert the silver sulfid sulfid and silversulfidthus produced, then l'eaching the oxidized mixture so as, to re-i move the coppercompounds therefrom, then treating the mixture of barium sulfate and.

silver sulfid with a chlorid' adapted to conert the'silver-si1lfid into silver chlorid, then leachin the mixture of barium'sulfate and silver chlorid with a solvent for silver chl'orid, then reducing the barium sulfate to barium sulfid, and then adding the barium sulfid to the. liquor fromwhich the copper; sulfid has been precipitated, so as toobtain a'mixture of barium sulfate and Zinc sulfid for-r'e-use.

6. A process for treating copper liquors,

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same-time to dissolve the said silver compound',then reducing the barium sulfate to barium sulfid, and then adding the barium sulfid to'theliquor from which the copper treating the mixtureyof barium sulfa-t silver sulfid with ,a solution of c sulfid-t0 the liquor from which the copper sulfid] hasbeeng precipitated, so as to obtaina-mixture of barium sulfate and zinc sulfid.

. v i V 75 'fWlliCll process consistsin first adding to-the .liquor amixtu'reof barium sulfate and zinc duoed, thenllea ching the copper compounds from the mixture obtained by the heating,

and silver sulfid-with a solution of chlorid of copper-and common salt, then reducing the barium sulfate to barium sulfid, and

from which the copper sulfid-has. beenprerium sulfate and zinc sulfid for re-use.

of two subscribing witnessesv JOHN HERBERT THWAITES.

' Vitnesses: JOSEPH MILLARD,

W. J: SKEnrnN treating copper liquors,

i'copper sulfid and silver sulfid thus produced,"-

- 8. A process for treating copper-liquors,

sulfid which hasirot been dried, then heat.- "ing in air the mix'ture of'barium sulfate,. copper sulfidfand silver sulfid thus pro "then adding the barium sulfid to the liquor -cipitated, so as :to obtainna mixture of'ba- In testimony whereof I have'signed' name toothis. specificationin the presenee ng the Commissioner ofmam.

into a ,soluble silver compound and at the 50 sulfid which has not been dried, then heatfid ofi'copper' and common salt and, subsea quently-leaching ,it with a, solution of com-j mon' salt, then' reducin'g the barium sulfate;

to' :barium. siilfid, then adding the barium thentreating the mixture ofzbarium. sulfate 

